In the prior art, identity authentication technology is used generally for guaranteeing the security of online trade. The nature of the identity authentication means that information (including confidential information or information of special hardware held by a person or unique biological feature of the person) owned by a peer cannot be counterfeited by any third party (except the authentication authority which is required in some solutions). And if the peer makes the authenticator believe that he has the information (by showing the information to authenticator or using method of zero-knowledge proof), the identity of the peer is authenticated. In order to prevent the information from being obtained or tampered illegally in process of transferring, technology of encryption/decryption is adapted generally. Encryption technology is a usual way for security and keeping secret by means of converting important data into unrecognizable code and then transferring the code. Only the corresponding key is input can the content of the important data be readable. Decryption is a reverse process of the encryption. Decryption technology is adapted to convert the obtained code information into its original data in the same or different way of encryption.
To prevent the information from being destroyed and secure the authenticity of the traders of both sides as well, signature technology is used. The signature technology includes digital signature and electronic signature. Digital signature means that signing a signature with electric codes formed by a series of symbols and codes generated by some cryptography algorithm instead of a handwriting signature or a stamp. As a mature technology with strong operability, digital signature is a general electric signature method used in e-business or e-office. Digital signature adopts a normalized process and a scientific method to authenticate the identity of a signatory and approve the electrical data content of an item. With the same function of the handwriting signature or the stamp, electric signature is a means that can identify the authenticity of traders of both sides in the electric files and guarantee security and reality and non-repudiation of the trade.
But for some trades with strictly time limit such as real-time stock trade, the time of local equipment, also called time source, might be unreliable because of technical or commercial reasons. The security of trade cannot be guaranteed by depending on identity authentication, encryption/decryption or signature only. So the time source which the trade is relied on is very important. Time source is the source where time comes from, especially the reliable time comes from. There are two sources for obtaining time, one is from the time of a server side, and the other is from the local time of a client side computer. But the local time of the client computer is unreliable, and the time of the server side cannot be obtained at any moment or anywhere. So the time source of the client computer should be calibrated according to the server side.